Simple reversed-phase liquid chromatographic assay for simultaneous quantification of free mycophenolic acid and its glucuronide metabolite in human plasma

A reversed-phase HPLC-UV method, involving simple instrumental setup and mobile phase without ion-pairing reagent, was developed and validated for direct simultaneous quantification of free mycophenolic acid (MPA) and its major metabolite MPA-glucuronide (MPAG) in human plasma. Both free MPA and MPAG were isolated from plasma samples using ultrafiltration prior to analysis. Each chromatographic run was completed within 13 min. The optimized method showed good performance in terms of specificity, linearity (r2 = 0.9999), sensitivity (limit of quantitation (LOQ): 0.005 mg/L for MPA; 1 mg/L for MPAG), and intra- and inter-day precision (R.S.D. < 7%). This assay was successfully applied to free MPA and MPAG measurements in clinical samples.